1. Field of the Invention
The invention relates to a wood planing machine, more particularly to a wood planing machine with a height retention mechanism for a cutter carriage.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional wood planing machine 10 is shown to include a machine base 11, left and right pairs of upstanding posts 12 (only one post 12 is shown in FIG. 2), a cutter carriage 13, and a height adjustment mechanism 20.
As illustrated, the machine base 11 has opposite mounting sides 111 spaced apart from each other in a transverse direction, and opposite feed-in and take-out sides spaced apart from each other in a longitudinal direction. The upstanding posts 12 extend upward from the machine base 11 at the mounting sides 111. The cutter carriage 13 is disposed above the machine base 11, and has opposite end portions 130 mounted movably on the upstanding posts 12 for sliding movement of the cutter carriage 13 along the upstanding posts 12. A cutter device 14 is mounted on the cutter carriage 13, and is rotatable about a horizontal axis that extends in the transverse direction.
The height adjustment mechanism 20 includes a transmission rod 23 disposed within the machine base 11 along the transverse direction, a pair of screw rods 21, 22 mounted rotatably on and extending upwardly from the machine base 11 at the mounting sides 111 to pass threadedly through the cutter carriage 13 at the opposite end portions 130 thereof. The screw rods 21,22 have lower ends 211, 221 coupled with the transmission rod 23 via pairs of bevel gears 222,232 which are also disposed in the machine base 11. A turning handle 24 is provided at the top end of one of the screw rods 21 such that rotation of the latter will cause the cutter carriage 13 to slide along the upstanding posts 12 so as to define a gap between the cutter carriage 13 and the machine base 11 for passage of a work piece (not shown) to be processed.
It is noted that height retention in the conventional wood planing machine 10 is achieved solely through the threaded engagement between the cutter carriage 13 and the screw rods 21, 22. In addition, non-synchronous rotation of the screw rods 21, 22 due to indirect rotation of the transmission rod 23 upon operation of the turning handle 24 may result in uneven height adjustment of the cutter carriage 13 relative to the machine base 11, thereby adversely affecting the quality of the planing operation.